cmd/tailscale/cli: fix TUNmode display on synology web page (#7064)

Fixes #7059

Signed-off-by: Jenny Zhang <jz@tailscale.com>

Signed-off-by: Jenny Zhang <jz@tailscale.com>
(cherry picked from commit 2d29f77b24)

cmd/tailscale/cli/web.html

@@ -100,7 +100,7 @@
 	</div>
 	{{ if .IsSynology }}
 		<div class="border border-gray-200 bg-orange-0 rounded-lg p-2 pl-3 pr-3 mb-8 width-full text-orange-800">
-			Outgoing access {{ if true }}enabled{{ else }}not configured{{ end }}.
+			Outgoing access {{ if .TUNMode }}enabled{{ else }}not configured{{ end }}.
 			<nobr><a href="https://tailscale.com/kb/1152/synology-outbound/"
 				class="font-medium link"
 				target="_blank"